A conventionally proposed low-temperature sintered ceramic body that is capable of being fired simultaneously with a conductor includes quarts (SiO2) and hexagonal and monoclinic celsian (BaAl2Si2O8) in its crystalline phase and has B/A of not greater than 0.2 and C/A of not less than 0.6, where A represents an X-ray intensity of a quarts (101) face, B represents an X-ray intensity of a monoclinic celsian (112) face, and C represents an X-ray intensity of a hexagonal celsian (101) face (see, for example, Japanese Patent Laid-Open No. 2008-105917). This proposed sintered body is expected to have an increased coefficient of thermal expansion and an enhanced chemical resistance. Another proposed sintered ceramic body includes Al, Si, Sr, and Ba as primary components and has Al2O3 crystals and at least one of hexagonal SrAl2Si2O8, (Sr,Ba)Al2Si2O8, and BaAl2Si2O8 in the structure (see, for example, Japanese Patent Laid-Open No. 2006-001755). This proposed sintered body is expected to have an increased mechanical strength and an improved dielectric characteristic. Still another proposed sintered ceramic body has a content of glass powder in a range of 25% to 34% and a content of alumina ceramic power as a mixture of fine particles and coarse particles in a range of 66% to 75% and average particle diameters of the glass powder and the ceramic powder of less than 1 μm (see, for example, Japanese Patent Laid-Open No. 2001-010858). This proposed sintered body is expected to be densified by low-temperature sintering at a temperature of not higher than 1000° C.